TCB Publications - Abstract

GULL2003
Steered Molecular Dynamics (SMD) simulations of the
mechanosensitive channel of large conductance, MscL, were used to investigate how forces arising from membrane tension induce gating of the channel. A homology
model of the closed form of MscL from E. coli was subjected to external forces of 35-70pN applied to residues near the membrane-water
interface. The magnitude and location of these forces
corresponded
to those determined from the lateral pressure profile computed
from
a lipid bilayer simulation. A fully expanded state was obtained
on the
10ns time scale that revealed the mechanism for transducing
membrane
forces into channel opening. The expanded state agrees well with
proposed
models of MscL gating, in that it entails an iris-like expansion
of the
pore accompanied by tilting of the transmembrane helices. The
channel
was most easily opened when force was applied predominantly on the
cytoplasmic side of MscL. Comparison of simulations in which
gating
progressed to varying degrees identified residues that pose steric
hindrance to channel opening.

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